The present invention relates to apparatus for manipulating rod-shaped articles, especially for manipulating filter rod sections. More particularly, the invention relates to improvements in apparatus for converting groups of two or more coaxial rod-shaped articles which are moved sideways into a single row of rod-shaped articles which also move sideways and are located exactly or nearly exactly one behind the other. Such apparatus can be used in filter cigarette making or like machines wherein filter rod sections of multiple unit length are subdivided into shorter filter rod sections or plugs for introduction into the spaces between pairs of coaxial plain cigarettes to form therewith assemblies of three rod-shaped articles each. Such assemblies can be converted into filter cigarettes of double unit length by convoluting an adhesive-coated uniting band around each shorter filter rod section and the adjacent end portions of the respective plain cigarettes. As a rule, the filter rod sections of multiple unit length are withdrawn from a magazine or hopper by a fluted conveyor and are transported past one or more knives which subdivide each filter rod section into a group of two or more coaxial filter plugs. Such groups must be converted into a single row wherein the filter plugs are located one behind the other and wherein the filter plugs preferably move sideways for convenient introduction into the spaces between successive pairs of coaxial plain cigarettes of unit length.
German Pat. No. 1,272,795 discloses an apparatus wherein a first drum-shaped conveyor removes filter rod sections from the magazine and a rotary second or staggering conveyor converts the groups of coaxial filter plugs into a single row of filter plugs wherein successive filter plugs are located one behind the other, as considered in the direction of movement of the staggering conveyor. The two conveyors are driven to rotate in opposite directions and the pitch circle of the first conveyor is intersected by the pitch circle of the second conveyor. The second conveyor comprises several wheel- or disk-shaped portions which are adjacent to each other and each of which can accept one filter plug of a group of two or more coaxial filter plugs in a peripheral flute of the first conveyor. The disk-shaped sections are eccentric with respect to each other and their pitch circles have a common tangent at a transfer station where the filter plugs leave the second conveyor. The distance between the flutes of the disk-shaped sections at a second transfer station where the second conveyor receives filter plugs from the first conveyor equals t/n wherein t is the distance between neighboring flutes of the first conveyor and n is the number of filter plugs in a flute of the first conveyor. The intersecting portions of the pitch circles of the two conveyors are substantially normal to each other; consequently, each filter plug must abruptly change the direction of its movement through 90.degree. during transfer from a flute of the first conveyor into a flute of a disk-shaped section of the second conveyor. The stresses to which the filter plugs are subjected during such abrupt transfer in a high-speed filter cigarette making machine can be withstood reasonably well by filter plugs containing exclusively acetate fibers but such stresses often result in damage to so-called combination filter plugs which contain granular and/or pulverulent filter material as well as to filter plugs containing acetate fibers together with pulverulent carbon or other solid material in finely comminuted form.
Another drawback of the just described apparatus is that it comprises a large number of complex precision-finished and hence expensive parts. This is due to the fact that the disk-shaped sections of the staggering conveyor are eccentric with respect to each other and must be provided with precision-finished internal gears receiving torque from discrete pinions which, in turn, receive motion from a complex transmission. The aforementioned German patent does not disclose the exact details of drive means for the sections of the staggering conveyor; in actual practice, the drive means for the two conveyors constitutes the most expensive, sensitive and complex portion of the apparatus.